The present invention relates to a heat pump type air conditioner in which a heat pump is operated using singly or in combination a new substitute refrigerant gas HFC (hydrofluorocarbon) 134a or HFC125, which, containing no chlorine, will not damage the ozone layer, and is nonflammable and nonpoisonous, and in which the flow of the refrigerant gas is reversible by changing over the flow passage of gas for cooling and heating.
To protect the ozone layer, use of chlorine-containing freons, notorious ozone layer killers, has to be totally stopped on the face of the earth as soon as possible. But simply replacing such freons as refrigerants with new ones will make the operation of air conditioners difficult.
Newly developed substitute refrigerant gases HFC134a and HFC125 contain no chlorine and will not damage the precious ozone layer. But these gases have a problem in that they are not compatible with an ordinary mineral lubricating oil and thus such gases have to be used in combination with a specially developed lubricating oil to operate existing heat pumps.
Mixing with combustible HFC refrigerant gas and use of ester series lubricating oil compatible with HFC refrigerant gas are being considered, but with no marked development.
I have already proposed a method and apparatus for operating a heat pump using a new substitute refrigerant gas HFC134a or HFC125 or their mixture. The point of our prior invention is to add an extra condenser to an existing condenser. By using two separate condensers, the condensing capacity is increased and mutual solubility between refrigerant gas HFC134a or HFC125 and a mineral lubricating oil improves.
But in the case of a heat pump device used both for cooling and heating, simply by increasing the heat exchange capacity of the condenser, refrigerant gas HFC134a or HFC125 may separate from a mineral lubricating oil due to insufficient liquefaction of refrigerant during heating because during heating, the refrigerant flows in a reverse direction and thus the condensers are used as evaporators and the evaporators as condensers.
One possible solution would be to add, separately or as a one-piece unit, an extra condenser 2' and an extra evaporator 3' to the existing condenser 2 and the evaporator 3, respectively, as shown in FIG. 2 to increase their respective condensing power. But this solution has a problem in that when either the evaporator or condenser is used as an evaporator, its heat absorbing capacity tends to be so large that the refrigerant loses its cooling capacity by the time it leaves the evaporator or the condenser as the evaporator. While the atmospheric temperature is high, the excessively heated refrigerant cannot cool the compressor.
The compressor is generally cooled by the refrigerant returned, which is gasified but still cool enough to have a sufficient cooling capacity.
An object of the present invention is to provide a heat pump which can increase the heat exchange capacity of either of the evaporator and the condenser whenever it is used as a condenser so that the refrigerant gas is sufficiently liquefied and compatible well in a mineral lubricating oil.
That is, according to the present invention, both during cooling and heating, only either of the condenser and the evaporator that is being used as a condenser is increased, while the other's heat exchange capacity remains unchanged, so that the refrigerant gasified by the evaporator is still cool enough to be able to cool the compressor.